The goal of this project is to elucidate the molecular events of the formation of the head of bacteriophage T4 from its subunits and the subsequent steps of head-maturation, which occur after the formation of the protein coat and up to the time it can accept a tail. Attention will be focused on the role of the various protein components of the head which become cleaved and the questions of when and how the DNA is packaged. We will make use of the vast knowledge of the genetics of this phage, applying centrifugal and chromatographic methods to isolate and characterize the various phage components and intermediates of the head. Their protein constituents will be determined by SDS-gel electrophoresis and their structure examined in the electron microscope.